Prepreg sheet and method for producing fiber-reinforced composite material

Abstract

The purpose of the present invention is to provide a prepreg sheet containing a radical-polymerizable resin composition that imparts excellent mechanical properties to FRP and has excellent curability and storage properties. The prepreg sheet according to the present invention is obtained by impregnating a fiber with a radical polymerizable resin composition, and is characterized in that the radical polymerizable resin composition contains at least the following chemical formula [chemical formula 1]: [chemical formula 1] (in the formula, n is 2-100, and n is 1-10). The urethane (meth) acrylate compound (a) is represented by formula [chemical formula 2]: "chemical formula 2"-N = C = O, where M is other than formula [chemical formula 3]: "chemical formula 3", in which Q represents a monoalcohol compound residue containing an ethylenically unsaturated group), X represents a compound residue having two or more isocyanate groups, and M at least contains a compound residue represented by formula [chemical formula 2]: "chemical formula 2"-N = C = O, where Q represents a monoalcohol compound residue containing an ethylenically unsaturated group.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201780032945.3 (PCT / JP2017 / 013330) filed on March 30, 2017, entitled "Prepreg Sheet and Method for Manufacturing Fiber Reinforced Composite Material", the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present application relates to a prepreg sheet and a method for manufacturing a fiber reinforced composite material, and particularly to a prepreg sheet having excellent mechanical strength and a method for manufacturing a fiber reinforced composite material using the same.

PRIOR ART

[0003] Fiber reinforced plastics (FRP) are used in various fields due to their light weight, high strength, and long life. In particular, FRP using carbon fibers or aramid fibers are used in various fields such as members of aircraft or automobiles, cement reinforcement materials, sports equipment, and the like due to their light weight and high strength.

[0004] There are several methods for manufacturing FRP, and as molding using a prepreg sheet obtained by impregnating a resin composition into a fiber, there are autoclave molding, oven molding, press molding, sheet winding molding, and the like. The molded product using the prepreg sheet is characterized by having a high content of fibers, and thus has excellent mechanical strength.

[0005] On the other hand, urethane (meth) acrylate compounds have been known to have excellent adhesion to carbon fibers, and have been used as a sizing agent for carbon fibers (for example, Patent Document 1). In addition, urethane (meth) acrylate compounds have been proposed to be used by mixing with resins having poor adhesion to reinforcing fibers because of their good adhesion to reinforcing fibers (for example, Patent Document 2).

[0006] [Patent Document]

[0007] [Patent Document]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 11-200252

[0009] [Patent Document 2] Japanese Patent Application Laid-Open No. 62-292839

SUMMARY OF THE INVENTION

[0010] [Problems to be Solved by the Invention]

[0011] However, the urethane (meth) acrylate compounds described in Patent Documents 1 and 2 described above cannot obtain sufficient mechanical properties when used as a composite material with a reinforcing fiber, and thus there is a problem in that a molded article having practical mechanical strength cannot be obtained.

[0012] In addition, as the matrix resin of the prepreg sheet, there are epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, and the like, but the current situation is that there is no matrix resin that satisfies FRP mechanical properties, hardenability, surface properties, and the like in a well-balanced manner. For example, a prepreg sheet using an epoxy resin as the matrix has excellent mechanical properties, but has a problem in that a high temperature and a long time are required for hardening, and lacks storage properties. A vinyl ester resin or an unsaturated polyester resin has excellent hardenability and storage properties, but has a problem in that the mechanical properties are insufficient.

[0013] Thus, an object of the present application is to provide a prepreg sheet containing a radical polymerizable resin composition that solves the above-described problems, imparts excellent FRP mechanical properties, and has excellent hardenability and storage properties.

[0014] [Means for solving the problem]

[0015] As a result of diligent studies made by the present inventors and the like in view of the above object, it has been found that a radical polymerizable resin composition containing a urethane (meth) acrylate compound containing an isocyanate group and a vinyl unsaturated group is suitable as a radical polymerizable resin composition for a prepreg sheet.

[0016] That is, the prepreg sheet of the present application is a prepreg sheet obtained by impregnating a radical polymerizable resin composition in a fiber, and is characterized in that the radical polymerizable resin composition contains at least a chemical formula [Chemical Formula 1] shown below:

[0017] [Chemical Formula 1]

[0018]

[0019] (Note that, in [Chemical Formula 1], n is 2 to 100, X is a compound residue having two or more isocyanate groups, and M contains at least a formula [Chemical Formula 2] shown below:

[0020] [Chemical Formula 2]

[0021] -N=C=O

[0022] and a formula [Chemical Formula 3] other than the above:

[0023] [Chemical Formula 3]

[0024]

[0025] Additionally, in formula [Chemical 3], Q represents a urethane (meth)acrylate compound (a) containing a monool compound residue with an ethylene unsaturated group.

[0026] Furthermore, in a preferred embodiment of the prepreg sheet of the present invention, the aforementioned chemical formula [Chemical 1] is derived from the following chemical formula [Chemical 4]:

[0027] [Chemistry 4]

[0028]

[0029] (However, in the formula, n is 1 to 5000, X is a compound residue having two or more isocyanate groups, Y is an alcohol compound residue having two or more hydroxyl groups, and M at least includes formula [Chemical 5]:)

[0030] [Chemistry 5]

[0031] -N=C=O

[0032] And its exterior is of formula [Chemistry 6]:

[0033] [Chemistry 6]

[0034]

[0035] Additionally, in formula [Chemical 6], Q represents a monool compound residue containing an ethylene unsaturated group.

[0036] In addition, in a preferred embodiment of the prepreg sheet of the present invention, the aforementioned urethane (meth)acrylate compound (a) contains 0.1 to 12% by weight of isocyanate groups.

[0037] In addition, in a preferred embodiment of the prepreg sheet of the present invention, the amount of polymeric vinyl monomer in the aforementioned free radical polymerizable resin composition is 0 to 50% by weight.

[0038] In addition, in a preferred embodiment of the prepreg sheet of the present invention, the polymerizable vinyl monomer in the aforementioned free radical polymerizable resin composition comprises one or more selected from phenoxyethyl methacrylate, benzyl methacrylate, isobornyl methacrylate, and tricyclodecanediethanol dimethacrylate.

[0039] Furthermore, the method for manufacturing the fiber-reinforced composite material of the present invention is characterized by including a step of hardening the prepreg sheet of the present invention.

[0040] [The effects of the invention]

[0041] According to the present invention, it is advantageous to obtain fiber-reinforced composite materials with excellent mechanical properties, free radical polymerizable resin compositions with excellent hardening properties, and prepreg sheets with excellent storage properties. [Attached Image Description]

[0042] [ Figure 1 ] Figure 1 The IR spectrum of urethane (meth)acrylate component (a) having isocyanate and vinyl unsaturated groups in one embodiment of the present invention (Synthesis Example 1 described later). At 2270 cm⁻¹ -1 Isocyanate group absorption can be confirmed in the vicinity.

Implementation Method

[0043] The embodiments of the present invention are described in detail below, but the present invention is not limited to the following description as long as it does not deviate from its spirit. Furthermore, in the present invention, "(meth)acrylate" refers to both "acrylate" and "methacrylate".

[0044] <Composition of urethane (meth)acrylate resin (a)>

[0045] First, the urethane (meth) acrylate component (a) (hereinafter also referred to as component (a)) constituting the free radical polymerizable resin composition contained in the prepreg sheet is described.

[0046] Component (a) can be listed by the following chemical formulas [Chem. 7]:

[0047] [Chemistry 7]

[0048]

[0049] (However, in formula [Chem. 7], n is 2 to 100, X is a compound residue having two or more isocyanate groups, and M at least includes formula [Chem. 8]:

[0050] [Chemistry 8]

[0051] -N=C=O

[0052] And its exterior is of formula [Chemistry 9]:

[0053] [Chemistry 9]

[0054]

[0055] Additionally, in formula [Chemical 9], Q represents a monool compound containing an ethylene unsaturated group, and Q represents a carbamate (meth) acrylate compound (a).

[0056] Alternatively, component (a) contains at least the following chemical formula [Chemical 10]:

[0057] [Chemistry 10]

[0058]

[0059] The carbamate (meth)acrylate compound represented. In [Chemical 10], n is 1 to 5000, X is a compound residue having two or more isocyanate groups, Y is an alcohol compound residue having two or more hydroxyl groups, and M at least includes the formula [Chemical 11]:

[0060] [Chemistry 11]

[0061] -N=C=O

[0062] And its exterior is of formula [Chemistry 12]:

[0063] [Chemistry 12]

[0064] In addition, in formula [Chemical 12], Q represents a monool compound residue containing an ethylene unsaturated group.

[0065] In this invention, if a compound having two or more isocyanate groups is reacted with a monool compound containing an ethylene unsaturated group, the compound described in [Chemical 7] above can be obtained.

[0066] Furthermore, in this invention, if a compound having two or more isocyanate groups is reacted with a monool compound containing an ethylene unsaturated group and an alcohol compound having two or more hydroxyl groups, the compound described in [Chemical 10] above can be obtained.

[0067] When synthesizing the compounds described in [Chemical 7] and [Chemical 10], the number of moles of isocyanate groups from the isocyanate compound is set to be greater than the total number of moles of hydroxyl groups from the monool compound containing an ethylene unsaturated group and the alcohol compound having two or more hydroxyl groups.

[0068] Regarding the synthesis reaction temperature, from the viewpoint of preventing gelation during synthesis with vinyl unsaturated groups, it is preferable to react at 40–140°C, and more preferably at 70–110°C.

[0069] The reaction time is preferably extended until the amount of residual isocyanate groups becomes constant, that is, the hydroxyl groups are consumed. The endpoint of the reaction can be confirmed by titrating to quantify the isocyanate groups or by tracking the absorption of isocyanate groups in an infrared absorption spectrum (hereinafter referred to as IR) (around 2270 cm⁻¹).

[0070] During the reaction, the synthesis can also be carried out in a system with polymerizable monomers or organic solvents that do not react with isocyanate groups, as needed, and known catalysts and polymerization inhibitors can be used.

[0071] The catalyst can be an acidic catalyst or a basic catalyst, preferably a tin compound such as dibutyltin dilaurate or dibutyltin diacetate, which has high activity. From the viewpoint of storage stability, the amount of catalyst added relative to the feed weight can be 0 to 200 ppm, preferably 0 to 100 ppm, and more preferably 0 to 50 ppm.

[0072] The isocyanate groups contained in component (a) are preferably 0.1 to 12% by weight, more preferably 0.3 to 8% by weight. If the content is less than 0.1% by weight, the adhesion to carbon fibers is poor, and there is a concern that sufficient compressive strength and interlaminar shear strength cannot be obtained. If the content exceeds 12% by weight, there is a concern that the flexural strength or tensile strength will decrease, and the balance of mechanical properties will break down.

[0073] There is no particular limitation on the equivalent of the vinyl unsaturated group of the urethane (meth)acrylate compound contained in component (a), but when it reaches 1500 g / eq or more, there is a concern that the balance of mechanical properties (flexural strength, tensile strength, compressive strength, interlaminar shear strength) will deteriorate and the heat resistance of the molded article will decrease.

[0074] <Isocyanate compounds>

[0075] Isocyanate compounds having two or more isocyanate groups include, for example, aromatic isocyanate compounds such as 1,3-xylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, and m-tetramethylxylene diisocyanate; hydrogenated xylene diisocyanate (1,3-bis(isocyanate group) Alicyclic isocyanate compounds such as (methyl)cyclohexane, isophorone diisocyanate, norbornene diisocyanate, dicyclohexylmethane diisocyanate, hydrogenated methylene biphenyl diisocyanate, and 1,4-cyclohexane diisocyanate; aliphatic isocyanate compounds such as 1,6-hexamethylene diisocyanate and trimethylene diisocyanate; trifunctional isocyanates having a tripolymerized isotricyanate ring of a difunctional isocyanate compound; and commercially available isocyanate prepolymers modified with polyols. These isocyanate compounds can be used alone or in combination of two or more. From the viewpoint of heat resistance, weather resistance, and storage stability, alicyclic isocyanate compounds are particularly preferred.

[0076] <Alcohol compounds>

[0077] Alcohol compounds having two or more hydroxyl groups include aliphatic alcohols, etherified diols, and polyester polyols.

[0078] Examples of chain-like aliphatic alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,4-butenediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentanediol, 2-ethyl-2-methylpropane-1,3-diol, and 2-butyl-2-ethylpropane-1,3-diol. 3-Diol, 1,6-Hexanediol, 3-Methyl-1,5-pentanediol, 2-Ethyl-1,3-hexanediol, 2,4-Dimethyl-1,5-pentanediol, 2,2,4-Trimethyl-1,3-pentanediol, 1,7-Heptanediol, 1,8-Octandiol, 1,9-Nonanediol, 1,10-Decanediol, Diethylene glycol, Triethylene glycol, Dipropylene glycol, Polypropylene glycol, Polyethylene glycol. Cyclic aliphatic alcohols include hydrogenated bisphenol A, tricyclodecanediethanol, spiroglycol, etc. Among these, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol are preferred from the viewpoint of resin viscosity or the mechanical properties of the cured product.

[0079] Etherified bisphenols include, for example, diols obtained by the addition reaction of bisphenol A with an epoxide, and diols obtained by the bromination of the adduct of bisphenol A with an epoxide. The epoxide is preferably ethylene oxide or propylene oxide, and the average number of moles of the epoxide added is preferably 2 to 16 moles relative to 1 mole of bisphenol A.

[0080] Polyester polyols may include unsaturated and / or saturated acids; those polycondensed with the aforementioned aliphatic alcohols and etherified bisphenols. Examples of unsaturated acids include maleic anhydride, maleic acid, and fumaric acid. Examples of saturated acids include phthalic acid, terephthalic acid, isophthalic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, succinic acid, sebacic acid, alkylsuccinic acid, alkenylsuccinic acid, ivonic acid, biphenyl dicarboxylic acid, naphthalene dicarboxylic acid, 5-tert-butyl-1,3-benzenedicarboxylic acid, and ester-forming derivatives of their anhydrides, lower alkyl esters, acid halides, etc. From the viewpoint of resin viscosity and the mechanical properties of the cured product, a polyester polyol obtained by polycondensation of one or more of terephthalic acid, isophthalic acid and their ester-forming derivatives with one or more of 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol is particularly preferred.

[0081] These alcohol compounds can be used alone or in combination of two or more. Furthermore, polyols with three or more nucleotides can also be used without impairing the effects of the present invention. Examples of polyols with three or more nucleotides include glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, etc., which can be used alone or in combination of two or more.

[0082] <Monol compounds containing vinyl unsaturated groups>

[0083] Monool compounds containing vinyl unsaturated groups refer to (meth)acrylates containing hydroxyl groups, such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, diacrylate isocyanurate, etc.

[0084] These monool compounds containing vinyl unsaturated groups can be used alone or in combination of two or more. Furthermore, among these monool compounds containing vinyl unsaturated groups, 2-hydroxyethyl (meth)acrylate is preferred from the viewpoint of resin viscosity or the mechanical properties of the cured product. Additionally, when heat resistance is necessary, pentaerythritol tri(meth)acrylate is preferred.

[0085] Polymerization inhibitors can be polyphenolic polymerization inhibitors such as hydroquinone, p-benzoquinone, methylhydroquinone, and trimethylhydroquinone; heterocyclic compounds such as phenothiazines; and nitroxyl radicals such as 2,2,6,6-tetramethylpiperidine-1-oxy. From the viewpoint of preventing gelation during synthesis with vinyl unsaturated groups or polymerizable monomers, the amount of polymerization inhibitor added is preferably 100 to 2000 ppm relative to the feed weight.

[0086] <Free radical polymerizable resin composition>

[0087] The free radical polymerizable resin composition of the present invention can refer to a resin composition for making prepreg sheets, which may be composed of a urethane (meth)acrylate compound (a), a polymerizable monomer, a curing agent, and an accelerator. Among these, the polymerizable monomer may be incorporated into the prepreg sheet to provide the necessary adhesiveness. Adhesiveness can refer to the degree of stickiness of the sheet surface.

[0088] In the case of prepreg sheets, the required adhesiveness (degree of adhesion of the sheet surface) varies depending on the molding method, ranging from a stringy state to an adhesion that allows it to adhere to vertical sections, and even to a degree that prevents adhesion even when stacked. This adhesiveness varies depending on the type and amount of polymeric vinyl monomers used and can be appropriately set.

[0089] In addition, the amount of necessary polymerizable vinyl monomers, etc., varies depending on the molecular weight of the urethane acrylate resin and is not specifically limited.

[0090] Furthermore, the polymerizable monomer is preferably one that does not react with isocyanate at room temperature. Examples of polymerizable monomers that do not react with isocyanate at room temperature include vinyl monomers, monofunctional acrylates, and polyfunctional acrylates. When polymerizable monomers that react with isocyanate groups are incorporated, there are concerns that the reaction may occur during storage, leading to increased viscosity and decreased workability, or that sufficient mechanical properties may not be obtained. Examples of vinyl monomers include styrene, vinyltoluene, α-methylstyrene, and vinyl acetate. In addition, examples of monofunctional acrylates include methyl methacrylate, benzyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, tetrahydrofuran methyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, norbornyl methacrylate, dicyclopentenyl methacrylate, and dicyclopentenyl methacrylate. Examples of polyfunctional acrylates include ethylene glycol dimethacrylate, 1,3-propanediol dimethacrylate, 1,4-butanediol dimethacrylate, neopentyl glycol dimethacrylate, diethylene glycol dimethacrylate, tripropylene dimethacrylate, norbornene diallyl dimethacrylate, tricyclodecane diallyl dimethacrylate, ethylene oxide addition bisphenol A dimethacrylate, propylene oxide addition bisphenol A dimethacrylate, trimethylolpropane trimethacrylate, and tris(2-(meth)acryloyloxyethyl)isocyanurate. These polymerizable monomers can be used alone or in combination of two or more.

[0091] From the viewpoint of the adhesive or mechanical properties of the prepreg after sheeting, styrene, benzyl methacrylate, tetrahydrofuran methyl methacrylate, cyclohexyl methacrylate, isoborneol methacrylate, norborneol methacrylate, dicyclopentenyl methacrylate, dicyclopentenoxyethyl methacrylate, and phenoxyethyl methacrylate are preferred. Polyfunctional acrylates are preferably polymerizable monomers having any of the following: ethylene glycol dimethacrylate, norbornene diallyl dimethacrylate, tricyclodecane diallyl dimethacrylate, ethylene oxide addition bisphenol A dimethacrylate, propylene oxide addition bisphenol A dimethacrylate, and tris(2-acryloyloxyethyl)isocyanurate, etc.

[0092] Furthermore, in a preferred embodiment of the prepreg sheet of the present invention, the polymerizable vinyl monomer in the aforementioned free radical polymerizable resin composition may include one or more selected from phenoxyethyl methacrylate, benzyl methacrylate, isobornyl methacrylate, and tricyclodecanediethanol dimethacrylate. From the viewpoint of mechanical property balance, phenoxyethyl methacrylate, benzyl methacrylate, and styrene are particularly preferred; from the viewpoint of heat resistance, isobornyl methacrylate and tricyclodecanediethanol dimethacrylate are particularly preferred. The amount of polymerizable vinyl monomer blended is adjusted according to the required adhesiveness of the prepreg (the degree of adhesion of the sheet surface: varies depending on the molding method), and is preferably in the range of 0 to 50% by weight. Further, when the molecular weight of the urethane acrylate is 500 to 1500, from the viewpoint of adhesiveness and the physical properties of the molded article, it is preferably blended in the range of 0 to 25% by weight. When the content exceeds 50% by weight, there is a concern that the reduction in urethane acrylate content may adversely affect the properties of the prepreg and the physical properties of the molded article, so it is not preferred.

[0093] Curing agents that can be used in the free radical polymerizable resin composition contained in the prepreg film of the present invention include organic peroxide systems, such as ketone peroxide systems like methyl ethyl ketone peroxide and acetylacetone peroxide; diacyl peroxide systems like benzyl peroxide; peroxy ester systems like benzoic acid t-butyl peroxide; hydroperoxide systems like cumene hydroperoxide; dialkyl peroxide systems like diisopropylphenyl peroxide; and peroxy dicarbonate systems like bis(4-tert-butyrylhexyl)peroxydicarbonate. These can be appropriately selected based on the molding temperature and the storage temperature of the prepreg film, and two or more can be used alone or in combination. The amount of curing agent added can be 0.05 to 5 parts by weight relative to 100 parts by weight of the free radical polymerizable resin composition.

[0094] To promote adhesion to fibers, the free radical polymerizable resin composition contained in the prepreg sheet of the present invention may contain an accelerator. Specific examples of accelerators include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, tin(II) octoate, etc., but are not limited to these as long as they promote the urethane esterification reaction. The amount of accelerator added may be 0.01 to 1.0 parts by weight relative to 100 parts by weight of the free radical polymerizable resin composition.

[0095] To adjust the viscoelasticity, inorganic particles or rubber particles may also be incorporated into the free radical polymerizable resin composition contained in the prepreg sheet of the present invention. Inorganic particles are not particularly limited, and examples include calcium carbonate, alumina, talc, titanium dioxide, and silica. Rubber components are not particularly limited, and examples include cross-linked rubber particles and core-shell rubber particles whose rubber components are encapsulated by a cross-linked polymer. The amount of these incorporated particles varies depending on the viscosity of the resin used, but is 5 to 50% by weight, preferably 10 to 30% by weight.

[0096] Next, the prepreg sheet of the present invention will be described. The fibers (also referred to as reinforcing fibers) used in the prepreg sheet of the present invention may include, but are not limited to, carbon fiber, glass fiber, polyaramid fiber, Zylon fiber, vinylon fiber, polyethylene fiber, boron fiber, basalt fiber, cellulose, etc. Furthermore, the reinforcing fiber content is 10-90% by weight, and from the viewpoint of mechanical properties and formability, it is preferably 30-80% by weight. There are no particular limitations regarding the surface treatment agent and shape (unidirectional, cross-cut, NCF, non-woven fabric, etc.) of the reinforcing fiber.

[0097] The prepreg sheet of the present invention can be obtained by conventional wet or hot-melt methods. The wet method involves dissolving a free-radical polymerizable resin composition in a solvent such as methyl ethyl ketone or toluene to reduce the viscosity of the composition, impregnating it with fibers, and then distilling off the solvent by heating to obtain the prepreg sheet. The type of solvent is not particularly limited as long as it does not react with isocyanate groups. Although it varies depending on the type of curing agent incorporated, a solvent with a boiling point of 50–150°C is preferred. The hot-melt method involves coating a resin film with a roller coater, then attaching reinforcing fibers and heating and pressing to obtain the prepreg sheet. This method can be selected depending on the fiber thickness or weaving method.

[0098] Furthermore, the prepreg sheet of the present invention is preferably used in fiber-reinforced composite materials containing carbon fiber reinforced plastics.

[0099] Furthermore, as described above, resin compositions for fiber-reinforced composite materials (including carbon fiber reinforced plastics) that can be used in the prepreg sheets of the present invention include resin compositions for fiber-reinforced composite materials (including carbon fiber reinforced plastics) composed of urethane (meth)acrylate compounds as shown in [Chemical 1] or [Chemical 4] above. As described above, in this case, the isocyanate group in the aforementioned urethane (meth)acrylate compound is preferably 0.1 to 12% by weight.

[0100] Furthermore, the method for manufacturing the fiber-reinforced composite material of the present invention is characterized by including a step of hardening the prepreg sheet of the present invention. The fiber-reinforced composite material of the present invention can be obtained by, for example, laminating the prepreg sheet obtained by the above method to a specific thickness, and then applying heat and pressure for hardening. Forming methods include autoclave forming, oven forming, sheet winding forming, and compression forming. The forming temperature is 60–200°C, preferably 100–180°C, the time is preferably 1–120 minutes, and the pressure is preferably -1–15 Bar. [Example]

[0101] The present invention will be further illustrated by the following examples, but the present invention is not limited to the following examples. In these examples, "parts" refers to parts by weight unless otherwise specified. The isocyanate group content in the synthesis examples is determined by dissolving each resin in dried toluene, adding excess di-n-butylamine solution to react, and then determining the remaining di-n-butylamine by reverse titration with hydrochloric acid.

[0102] [Synthesis example 1]

[0103] Synthesis of urethane (meth)acrylate resins

[0104] 535.3 parts of isophorone diisocyanate (manufactured by Evonik), 130.0 parts of phenoxyethyl methacrylate (LIGHT ESTER PO, manufactured by Kyoei Chemical Co., Ltd.), 0.02 parts of dibutyltin dilaurate, 108.0 parts of 1,3-propanediol (manufactured by DuPont), 226.4 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 0.04 parts of hydroquinone, and 0.26 parts of 4-methyl-2,6-di-tert-butylphenol were charged into a reaction vessel and reacted under airflow (0.2 L / min) at a temperature of 95–105 °C. The reaction was tracked by IR, and the endpoint was defined as the point where the absorption of isocyanate groups (around 2270 m⁻¹) became constant. The reaction took 3 hours. A urethane (meth)acrylate resin with an isocyanate group content of 1.0 wt% was obtained (the isocyanate group content in component (a) was 1.2 wt%).

[0105] [Synthesis example 2]

[0106] Synthesis of urethane (meth)acrylate resins

[0107] 530.6 parts of isophorone diisocyanate (manufactured by Evonik), 130.0 parts of phenoxyethyl methacrylate (LIGHT ESTER PO, manufactured by Kyoei Chemical Co., Ltd.), 0.02 parts of dibutyltin dilaurate, 112.7 parts of 1,3-propanediol (manufactured by DuPont), 226.4 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 0.04 parts of hydroquinone, and 0.26 parts of 4-methyl-2,6-di-tert-butylphenol were charged into a reaction vessel and reacted under airflow (0.2 L / min) at a temperature of 95–105 °C. The reaction was tracked by IR, and the endpoint was defined as the point where the absorption of isocyanate groups (around 2270 m⁻¹) became constant. The reaction took 3 hours. A urethane (meth)acrylate resin with an isocyanate group content of 0.3 wt% was obtained (the isocyanate group content in component (a) was 0.35 wt%).

[0108] [Synthesis example 3]

[0109] Synthesis of urethane (meth)acrylate resins

[0110] 571.1 parts of isophorone diisocyanate (manufactured by Evonik), 100.0 parts of phenoxyethyl methacrylate (LIGHT ESTER PO, manufactured by Kyoei Chemical Co., Ltd.), 0.02 parts of dibutyltin dilaurate, 55.3 parts of 1,3-propanediol (manufactured by DuPont), 273.3 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 0.04 parts of hydroquinone, and 0.26 parts of 4-methyl-2,6-di-tert-butylphenol were charged into a reaction vessel and reacted under airflow (0.2 L / min) at a temperature of 95–105 °C. The reaction was tracked by IR, and the endpoint was defined as the point where the absorption of isocyanate groups (around 2270 m⁻¹) became constant. The reaction took 3 hours. A urethane (meth)acrylate resin with an isocyanate group content of 6.4 wt% was obtained (the isocyanate group content in component (a) is 7.4 wt%).

[0111] [Synthesis Example 4]

[0112] Synthesis of urethane (meth)acrylate resins

[0113] The following components were added to a reaction vessel: isophorone diisocyanate trimer (manufactured by Evonik), phenoxyethyl methacrylate (LIGHT ESTER PO manufactured by Kyoei Chemical Co., Ltd.), dibutyltin dilaurate, pentaerythritol triacrylate (Aronix M-305 manufactured by Toa Synthetic Co., Ltd.), 248.2 parts, 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 0.04 parts, and 0.26 parts, 4-methyl-2,6-di-tert-butylphenol. The reaction was carried out under an air flow (0.2 L / min) at a temperature maintained at 95–105 °C. The reaction was monitored by IR spectroscopy, with the endpoint determined at the point where the isocyanate group absorption (around 2270 m⁻¹). The reaction took 2.5 hours. A urethane (meth)acrylate resin with an isocyanate group content of 1.7 wt% was obtained (the isocyanate group content in component (a) is 1.97 wt%).

[0114] [Synthesis example 5]

[0115] Synthesis of urethane (meth)acrylate resins

[0116] 529.7 parts of isophorone diisocyanate (manufactured by Evonik), 130.0 parts of phenoxyethyl methacrylate (LIGHT ESTER PO, manufactured by Kyoei Chemical Co., Ltd.), 0.02 parts of dibutyltin dilaurate, 115.0 parts of 1,3-propanediol (manufactured by DuPont), 225.0 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 0.04 parts of hydroquinone, and 0.26 parts of 4-methyl-2,6-di-tert-butylphenol were charged into a reaction vessel and reacted under airflow (0.2 L / min) at a temperature of 95–105 °C. The reaction was tracked by IR, and the endpoint was defined as the point where the absorption of isocyanate groups (around 2270 m⁻¹) became constant. The reaction took 3 hours. A urethane (meth)acrylate resin with an isocyanate group content of 0.06 wt% was obtained (the isocyanate group content in component (a) was 0.067 wt%).

[0117] [Synthesis example 6]

[0118] Synthesis of urethane (meth)acrylate resins

[0119] A reaction vessel was loaded with 620.0 parts of isophorone diisocyanate (manufactured by Evonik), 100.0 parts of phenoxyethyl methacrylate (LIGHT ESTER PO, manufactured by Kyoei Chemical Co., Ltd.), 0.02 parts of dibutyltin dilaurate, 29.3 parts of 1,3-propanediol (manufactured by DuPont), 250.4 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 0.04 parts of hydroquinone, and 0.26 parts of 4-methyl-2,6-di-tert-butylphenol, and reacted under air (0.2 L / min) at a temperature of 95–105 °C. The reaction was tracked by IR, and the endpoint was defined as the point where the absorption of isocyanate groups (around 2270 m⁻¹) became constant. The reaction took 3 hours. A urethane (meth)acrylate resin with an isocyanate group content of 12.1 wt% was obtained (the isocyanate group content in component (a) is 13.5 wt%).

[0120] [Synthesis Example 7]

[0121] Synthesis of acrylic epoxy resin

[0122] 689.9 parts of bisphenol A type epoxy compound (JER "#1001"), 127.6 parts of methacrylic acid, 1.64 parts of 2-methylimidazole, and 0.82 parts of monomethyl ether hydroquinone were charged into a reaction vessel. The reaction was carried out under air flow (0.2 L / min) at a temperature maintained at 110–120 °C for 10 hours. Afterwards, the mixture was diluted with 180.0 parts of phenoxyethyl methacrylate (LIGHT ESTER PO manufactured by Kyoei Chemical Co., Ltd.) to obtain an acrylic epoxy resin with an acid value of 2.4 mg / KOH.

[0123] [Synthesis example 8]

[0124] Synthesis of acrylic epoxy resin

[0125] A reaction vessel was filled with 622.3 parts of a phenolic varnish-type epoxy compound (DIC-manufactured EPICLON "N-740"), 294.0 parts of methacrylic acid, 2.75 parts of triphenylphosphine, and 0.91 parts of hydroquinone. The reaction was carried out under an air stream (0.2 L / min) at a temperature maintained at 110–120 °C for 8 hours. Afterwards, the mixture was diluted with 80.0 parts of phenoxyethyl methacrylate (Kyoei Chemical Co., Ltd., manufactured Light Esterpo) to obtain an acrylic epoxy resin with an acid value of 3.8 mg / KOH.

[0126] [Synthesis Example 9]

[0127] Synthesis of unsaturated polyester resin

[0128] A reaction vessel was filled with 360 parts phthalic anhydride, 282 parts fumaric acid, 90 parts ethylene glycol, and 399 parts propylene glycol. The mixture was subjected to a polycondensation reaction at 210°C for 11 hours under nitrogen flow (0.5 L / min) with stirring. Afterward, the mixture was diluted with 430 parts styrene monomer to obtain an unsaturated polyester resin.

[0129] [Synthesis Example 10]

[0130] Synthesis of urethane (meth)acrylate resins

[0131] A reaction vessel was loaded with 615.3 parts of isophorone diisocyanate (manufactured by Evonik), 0.02 parts of dibutyltin dilaurate, 124.2 parts of 1,3-propanediol (manufactured by DuPont), 260.2 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical), 0.05 parts of hydroquinone, and 0.30 parts of 4-methyl-2,6-di-tert-butylphenol. The reaction was carried out under airflow (0.2 L / min) at a temperature of 105–115 °C. The reaction was monitored by IR spectroscopy, with the endpoint determined at the point where the isocyanate group absorption (around 2270 m⁻¹). The reaction took 3 hours. A urethane (meth)acrylate resin with an isocyanate group content of 1.2 wt% was obtained.

[0132] [Synthesis Example 11]

[0133] Synthesis of urethane (meth)acrylate resins

[0134] 504.5 parts of isophorone diisocyanate (manufactured by Evonik), 180.0 parts of phenoxyethyl methacrylate (LIGHT ESTER PO, manufactured by Kyoei Chemical Co., Ltd.), 0.02 parts of dibutyltin dilaurate, 101.8 parts of 1,3-propanediol (manufactured by DuPont), 213.3 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 0.04 parts of hydroquinone, and 0.25 parts of 4-methyl-2,6-di-tert-butylphenol were charged into a reaction vessel and reacted under airflow (0.2 L / min) at a temperature of 95–105 °C. The reaction was tracked by IR, and the endpoint was defined as the point where the absorption of isocyanate groups (around 2270 m⁻¹) became constant. The reaction took 3 hours. A urethane (meth)acrylate resin with an isocyanate group content of 0.98 wt% was obtained (the isocyanate group content in component (a) was 1.2 wt%).

[0135] Modulation of free radical polymerizable compositions

[0136] To 100 parts of each resin in Synthetic Examples 1-6, 10, and 11, 0.02 parts of dibutyltin laurate as an accelerator and 1.5 parts of Perbutyl E (Nippon Oil peroxide ester type) as a curing agent were added to form a free radical polymerizable resin composition for prepreg sheets. To each resin in Synthetic Examples 7-9, 1.5 parts of Perbutyl E (Nippon Oil peroxide ester type) as a curing agent were added to form a free radical polymerizable resin composition for prepreg sheets.

[0137] Epoxy composition modulation

[0138] An epoxy resin composition was obtained by mixing 5 parts of dicyandiamine and 4 parts of urea derivative into 100 parts of bisphenol A type epoxy resin blend (Epikote#1001 / 828 = 50 / 50 manufactured by Japan Epoxy Resin).

[0139] Preparation of prepreg sheets

[0140] The above-prepared free radical polymerizable resin composition was coated onto release paper using a roller coater heated to 80°C to obtain a resin film. Next, carbon fibers (plain woven TORAYCA T700) were arranged in one direction on the resin film, and release paper was applied over them. Then, pressure was applied using a roller heated to 90°C to impregnate the resin. One side of the release paper was peeled off, and a polyethylene film was applied to obtain a prepreg sheet with a resin weight content of 33-35%. Prepreg sheets using the resins of Synthetic Examples 1-6, 10, and 11 were (a-1-6, a-10, a-11); prepreg sheets using the resins of Synthetic Examples 7-9 were (b-1-3); and prepreg sheets using the epoxy resin composition were (c-1).

[0141] For each prepreg sheet, the forming time was varied, and the sheets were pressed and formed. Test pieces were cut from the resulting sheets, and the flexural strength (JIS K 7074), interlaminar shear strength (JIS K 7078), and dynamic viscoelasticity were measured. In addition, regarding shelf life, the adhesive properties, post-forming appearance, and mechanical properties (3 months) were measured at 23°C.

[0142] Adhesive properties: based on the state of the prepreg immediately after fabrication.

[0143] ○ Maintain adhesiveness

[0144] △Increases tackiness while slightly decreases adhesiveness

[0145] × Significantly increases viscosity and loses adhesiveness

[0146] Visually evaluate the appearance after molding, ○>△>× indicates good>> bad.

[0147] Preparation of test pieces for mechanical property determination

[0148] Eleven prepreg sheets obtained above were stacked and pressed into shape at a forming temperature of 130°C and a forming pressure of 4 bar. Table 1 shows the results of forming time and mechanical properties, Table 2 shows the storage properties, and Table 3 shows the adhesive properties.

[0149]

[0150] [Table 2]

[0151]

[0152] [Table 3]

[0153]

[0154] in addition, Figure 1 The IR chromatogram shows the reaction endpoint of Synthesis Example 1.

[0155] The mechanical properties of the CFRP obtained in Examples 1-3 show a significant improvement in strengths compared to Comparative Examples 1-6. Example 4, exhibiting high heat resistance, also demonstrates superior mechanical properties compared to Comparative Example 2, which exhibits the same heat resistance. Regarding curing time, Examples 1-3 show excellent curing properties compared to Comparative Examples 5 and 6. Furthermore, in Table 1, DMA stands for Dynamic Mechanical Analysis. Additionally, good storage properties are also observed. Table 3 shows that while maintaining excellent mechanical properties, the adhesiveness of the prepreg film can be adjusted by adjusting the amount of polymerizable vinyl monomers incorporated.

[0156] [Industry availability]

[0157] The free radical polymerizable resin composition and prepreg film of the present invention are lightweight and high-strength, and therefore can be used in a variety of fields such as conveying equipment, industrial materials, civil engineering reinforcements, and sporting goods. However, their applications are not limited to these.

Claims

1. A prepreg sheet, which is formed by impregnating a free radical polymerizable resin composition into fibers, characterized in that, The free radical polymerizable resin composition contains at least one urethane (meth)acrylate compound (a) represented by the following chemical formula [Chemical 1]: [Chemistry 1] However, in formula [Chemical 1], n is 2 to 100, X is a compound residue having two or more isocyanate groups, and M at least includes formula [Chemical 2]: [Chemistry 2] -N=C=O, And its exterior is of formula [Chemistry 3]: [Chemistry 3] In addition, in formula [Chemical 3], Q represents a monool compound residue containing an ethylene unsaturated group.

2. The prepreg sheet as claimed in claim 1, wherein the aforementioned chemical formula [Chemical 1] is represented by the following chemical formula [Chemical 4]: [Chemistry 4] However, in the formula, n is 1 to 5000, X is a compound residue having two or more isocyanate groups, Y is an alcohol compound residue having two or more hydroxyl groups, and M at least includes formula [Chemical 5]: [Chemistry 5] -N=C=O, And its exterior is of formula [Chemistry 6]: [Chemistry 6] In addition, in formula [Chemical 6], Q represents a monool compound residue containing an ethylene unsaturated group.

3. The prepreg sheet of claim 1 or 2, wherein the aforementioned urethane (meth)acrylate compound (a) comprises 0.1 to 12% by weight of isocyanate groups.

4. The prepreg sheet according to any one of claims 1 to 3, wherein the amount of polymerizable vinyl monomer in the aforementioned free radical polymerizable resin composition is 0 to 50% by weight.

5. The prepreg sheet according to any one of claims 1 to 4, wherein the polymerizable vinyl monomer in the aforementioned free radical polymerizable resin composition comprises one or more selected from phenoxyethyl methacrylate, benzyl methacrylate, isobornyl methacrylate, and tricyclodecanediethanol dimethacrylate.

6. A method for manufacturing a fiber-reinforced composite material, characterized by comprising the step of hardening a prepreg sheet as claimed in any one of claims 1 to 5.

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